If South Africa keeps its promise to release all political prisoners by April 30, the Bush administration will ask Congress to respond by allowing the resumption of some trade with that country, U.S. officials say.

Once the prisoners are freed, the officials said Wednesday, President Bush will certify that South Africa has met most of the conditions imposed by Congress for resuming trade and has also made "substantial progress" toward establishing a non-racial democracy.If Congress doesn't object within 30 days, the administration can lift the sanctions. The consultation process could begin by early summer, said one official, who like others spoke on condition of anonymity.

The administration wants to reward South African President F.W. de Klerk for his efforts to dismantle apartheid, the system that allows South Africa's white minority to dominate the country's black majority.

But it has also been restrained by activists, including the African National Congress, who warn that sanctions should remain in place until South Africa's black majority is granted complete equality.

In New Zealand Thursday, a Cabinet minister said sporting, cultural and academic sanctions against South Africa could be relaxed "within a few weeks."

The government believes the measure would be an appropriate response to South Africa's efforts to repeal the main apartheid laws, said External Relations and Trade Minister Don McKinnon.

He said New Zealand wants to re-establish ties with groups within South Africa that already were integrated such as sports teams.

IN SOUTH AFRICA a judge Thursday postponed the kidnapping and assault trial of Winnie Mandela until March 6 to give police time to find a key witness allegedly abducted earlier this week.

Judge M.S. Stegmann agreed with prosecutors who said they could not proceed after one witness disappeared and two more refused to testify because they feared for their lives.

Winnie Mandela, wife of African National Congress leader Nelson Mandela, is one of four defendants charged with kidnapping and assaulting four young men at the Mandela's Soweto home outside Johannesburg in December 1988.

Three of the young men are the main state witnesses, and the fourth, 14-year-old Stompie Seipei, was found dead in 1989. The four defendants pleaded not guilty Monday.

One witness, Gabriel Mekgwe, disappeared Sunday night hours before he was to take the witness stand. The other witnesses, Kenneth Kgase and Tabiso Mono, refused to give evidence Wednesday. They said Mekgwe's disappearance made them fear for their lives.